1. Field of the Invention
The present invention relates to a mobile communication apparatus which precisely controls status information of the mobile communication apparatus displayed on an external device connected via a short-range communication link.
2. Description of the Related Art
A short-range wireless communication technique called Bluetooth® is well-known. By utilizing this short-range wireless communication technique, audio data can be transmitted from a mobile communication terminal, such as a cellular phone or a portable music player, to an external device, such as a headset without using an audio cable.
In Bluetooth®, “Advanced Audio Distribution Profile (A2DP)” and “Generic Audio/Video Distribution Profile (GAVDP)” are provided to transmit audio data in real time between two devices over a Bluetooth® link.
A “Hands-Free Profile (HFP)” is also provided for receiving incoming calls and making outgoing calls using the external device connected to the mobile communication terminal via the Bluetooth® link. The HFP is the standard profile used to control processes relating to incoming calls and outgoing calls executed by an external device such as a headset or a car-mounted device that is connected to the cellular phone via the Bluetooth® link.
Further, roaming service can be provided between telecommunication carriers, where some cellular phones can connect to a base station corresponding to a service area provided by a telecommunication carrier other than the telecommunication carrier to which the cellular phones belongs. However, this roaming service is not limited to the service between different domestic carriers. As a result, cellular phones can connect to base stations belonging to a telecommunication carrier in foreign countries. This international service is called international roaming.
Moreover, the HFP of the Bluetooth® standard includes a roaming status notification function, an operator's name finding function, a service status notification function, a status finding function and so on. In the roaming status notification function, a Roam-indicator identifying a roaming status is transmitted from the cellular phone to the external device with each change in the roaming status. For example, if the cellular phone is in a home area, the Roam-indicator indicates “0” and if the cellular phone is in a roaming area the Roam-indicator indicates “1”.
In the operator's name finding function, the cellular phone, responding to a request from the external device, transmits the operator's name to the external device. The operator's name corresponds to a name of the telecommunication carrier to which the cellular phone is currently connecting. In the service status notification function, a Service-indicator identifying whether a service is available or not is transmitted from the cellular phone to the external device with each change between no service and the presence of service. For example, if the cellular phone resides in a service area, the Service-indicator indicates “0”, and, if the cellular phone resides outside of the service area, the Service-indicator indicates “1”. In the status finding function, the cellular phone, responding to the external device, transmits the Roam-indicator, the Service-indicator, a Call-indicator, identifying if a call is active or not, and a Call-held indicator, identifying whether a call is held or not, to the external device.
However, according to the HFP, the roaming status indicator is not transmitted from the cellular phone to the external device when a user moves between roaming areas, For example if the user moves from Germany to France, when his/her cellular phone has a home area of Japan, the roaming status indicator is not transmitted. Thus is the case because both Germany and France are roaming areas for the cellular phone. Accordingly, an operator's name on a display of the cellular phone is not consistent with an actual carrier to which the cellular phone is connecting.
Also, if the cellular phone is located outside of the service area, according to the Bluetooth® standard, the cellular phone transmits the last roaming status and operator's name obtained just before going into no service.